Pouch exterior for secondary battery, pouch-type secondary battery using the pouch exterior, and method of manufacturing the pouch-type secondary battery

ABSTRACT

Disclosed are a pouch exterior capable of easily mounting an electrode assembly at an accurate position between accommodating parts, having an integrated form to minimize sealing parts contacting the air and to increase a lifetime of a battery, capable of preventing a rupture of the pouch exterior in an assembly process, and capable of increasing an energy density of a cell, a pouch-type secondary battery using the pouch exterior, and a method of manufacturing the pouch-type secondary battery. A pouch exterior for a secondary battery, according to the present disclosure, includes two corresponding accommodating parts configured to mount an electrode assembly therebetween and symmetrically formed at both sides by disposing a protruding part therebetween, and is folded along two folding lines outside a center pan of the protruding part by vertically mounting a side surface of the electrode assembly on the protruding part, such that folded parts surround side edges of the electrode assembly.

TECHNICAL HELD

The present disclosure relates to a pouch exterior for a secondarybattery, a pouch-type secondary battery using the pouch exterior, and amethod of manufacturing the pouch-type secondary battery, and moreparticularly, to a pouch exterior for a secondary battery, the pouchexterior being formed in an improved shape to increase an energy densityof a cell, a pouch-type secondary battery using the pouch exterior, anda method of manufacturing the pouch-type secondary battery. The presentapplication claims priority under 35 U.S.C. § 119 to Korean PatentApplication No. 10-2016-0117301 filed on Sep. 12, 2016, and KoreanPatent Application No. 10-2017-0106833 filed on Aug. 23, 2017, in theRepublic of Korea, and under 35 U.S.C. § 365 to PCT/KR2017/009440 filedon Aug. 29, 2017, the disclosures of which are incorporated herein byreference.

BACKGROUND

Secondary batteries are broadly used as power sources of mobile devicessuch as cellular phones, laptop computers, and camcorders. Particularly,use of lithium secondary batteries is rapidly increased due toadvantages thereof, e.g., a high operating voltage and a high energydensity per unit weight.

The lithium secondary batteries mostly use lithium-based oxide as apositive electrode active material and use a carbon material as anegative electrode active material. In general, the lithium secondarybatteries are divided into lithium ion batteries, lithium ion polymerbatteries, and lithium polymer batteries depending on electrolyte types,or are divided into cylindrical, prismatic, and pouch-type secondarybatteries depending on battery shapes. Typically, in terms of batteryshapes, the prismatic and pouch-type secondary batteries having smallthicknesses and thus usable in products such as cellular phones arehighly demanded.

Particularly, much attention is focused on the pouch-type secondarybatteries, which have no restriction in shape and size, are easilyassemblable through thermal fusion, are capable of easily discharging agas or a liquid in an abnormal state, and thus are properly useable toproduce light and thin cells. In general, a pouch-type secondary batteryhas a structure in which an electrode assembly is embedded in a pouchexterior configured as an aluminum laminate sheet. That is, thepouch-type secondary battery is manufactured by forming an accommodatingpart for mounting an electrode assembly therein, in an aluminum laminatesheet, mounting the electrode assembly in the accommodating part, andthermally fusing an additional aluminum laminate sheet separate from orextending from the aluminum laminate sheet.

The accommodating part may be formed in the pouch exterior bycompressing the aluminum laminate sheet having a thickness of about 113μm using a die and a punch based on a method similar to a deep drawingprocess. However, since the above-described thin aluminum laminate sheetmay be, for example, ruptured while being compressed, in general, anaccommodating part having a depth equal to or greater than 15 mm may notbe easily formed.

In a separate-type pouch exterior, since two units of aluminum laminatesheets are overlapped and sealed together, two accommodating partshaving mounted an electrode assembly therebetween should be overlappedwith each other to an accurate position to manufacture a secondarybattery. If the electrode assembly is not mounted at the accurateposition, since an internal short circuit is caused, a guide device isadditionally required and thus manufacturing costs are increased. Inaddition, since the two units of the aluminum laminate sheets arecombined at four sides to generate sealed parts, all of the four sidesmay contact the air, air may easily permeate thereinto when used for along time, and thus a lifetime of the battery may be reduced.

To solve the above problems, a variety of technologies related to amethod of forming two corresponding accommodating parts in a single unitof an aluminum laminate sheet, overlapping the accommodating parts witheach other, and sealing three sides thereof are disclosed.

FIG. 1 is a top view of a pouch exterior 10 of a conventional three-sidesealed pouch-type secondary battery. FIG. 2 illustrates sequentialcross-sectional views for describing a method of manufacturing apouch-type secondary battery 40 using the pouch exterior 10 of FIG. 1,taken along a line II-II′ of FIG. 1. FIG. 3 is a top view of thepouch-type secondary battery 40 manufactured using the method of FIG. 2.

Initially, referring to FIGS. 1 and 2(a), two accommodating parts 20 aand 20 b having perfectly corresponding shapes and sizes are formed in asingle unit of the pouch exterior 10 to be spaced apart from each otherby a predetermined distance d greater than a thickness of an electrodeassembly 30.

Then, the electrode assembly 30 is mounted in the accommodating part 20a or 20 b at a side as shown in FIG. 2(b), a center part F between theaccommodating parts 20 a and 20 b is folded as shown in FIG. 2(c) tooverlap the accommodating parts 20 a and 20 b as shown in FIG. 2(d), andthree sides other than the folded side are sealed (S), therebymanufacturing the pouch-type secondary battery 40 illustrated in FIG. 3.

According to the above-described technology of manufacturing thepouch-type secondary battery 40, a depth t of the accommodating parts 20a and 20 b formed in the pouch exterior 10 may be reduced to about ahalf of a cell thickness, and one of four sides of the pouch-typesecondary battery 40 (near the folded center part F) may be maintainedin a sealed state.

However, when the pouch exterior 10 is compressed to form the twoadjacent accommodating parts 20 a and 20 b, since the center part F tobe folded elongates in two directions to generate the accommodatingparts 20 a and 20 b, compared to a case in which the center part Felongates only in a single direction, mechanical strength of the centerpart F is unavoidably reduced and thus the center part F may be easilyruptured when the accommodating parts 20 a and 20 b are formed and/orwhen the center part F is folded. Therefore, the accommodating parts 20a and 20 b are formed to be spaced apart from each other by thepredetermined distance d, and a margin of about 1.5 mm to 3 mm is givennear the center part F to be folded to fold the pouch exterior 10, inconsideration of a bent shape of the folded part of the pouch exterior10.

A high capacity and a small size of a pouch-type secondary battery arerequired by many clients and various structures and processes are beingresearched/developed to satisfy the requirements of the clients.Particularly, many researches are focused on a method of increasing thecapacity of a pouch-type secondary battery using an unnecessary space.

However, in the conventional three-side sealed pouch-type secondarybattery 40 described above in relation to FIGS. 1 to 3, a folded part wcorresponding to an unnecessary space is generated and protrudes outwarddue to the margin of about 1.5 mm to 3 mm, which is given near thecenter part F to be folded to fold the pouch exterior 10. The foldedpart w serves as a restriction on a cell capacity, reduces an energydensity in a module/pack, is disadvantageous for a cooling structure,and thus should be improved.

As described above, a single unit of a pouch exterior capable ofminimizing a defect rate by preventing a rupture of the pouch exteriorwhen electrode assembly accommodating parts are formed and/or when thepouch exterior is folded to overlap the accommodating parts, and nothaving an unnecessary space to increase an energy density of a cell ishighly required.

SUMMARY

The present disclosure is designed to solve the problems of the relatedart, and therefore the present disclosure is directed to providing apouch exterior capable of easily mounting an electrode assembly at anaccurate position between accommodating parts, having an integrated formto minimize sealing parts contacting the air and to increase a lifetimeof a battery, capable of preventing a rupture of the pouch exterior inan assembly process, and capable of increasing an energy density of acell.

The present disclosure is also directed to providing a pouch-typesecondary battery using the pouch exterior, and a method ofmanufacturing the pouch-type secondary battery.

These and other objects and advantages of the present disclosure may beunderstood from the following detailed description and will become morefully apparent from the exemplary embodiments of the present disclosure.Also, it will be easily understood that the objects and advantages ofthe present disclosure may be realized by the means shown in theappended claims and combinations thereof.

In one aspect of the present disclosure, there is provided a pouchexterior for a secondary battery, the pouch exterior including twocorresponding accommodating parts configured to mount an electrodeassembly therebetween and symmetrically formed at both sides bydisposing a protruding part therebetween, and folded along two foldinglines outside a center part of the protruding part by verticallymounting a side surface of the electrode assembly on the protrudingpart, such that folded parts surround side edges of the electrodeassembly.

A length of the pouch exterior between the two folding lines maycorrespond to a thickness of the electrode assembly.

A depth of a bottom edge of each accommodating part away from theprotruding part may be greater than a depth of a bottom edge of theaccommodating part close to the protruding part such that a bottomsurface of the accommodating part may be inclined.

A width of a top surface of the protruding part may be greater than zeroand less than a thickness of the electrode assembly.

A depth of a bottom edge of each accommodating part away from theprotruding part may be equal to or greater than ½ of a thickness of theelectrode assembly. A depth of a bottom edge of the accommodating partclose to the protruding part may be equal to or greater than ½ of avalue obtained by subtracting a width of a top surface of the protrudingpart from the thickness of the electrode assembly.

Bottom edges of the two accommodating parts close to the protruding partmay serve as the two folding lines.

The accommodating parts may not be connected to each other.

Outer sides of the accommodating parts opposite the protruding part maybe extended relatively long.

In another aspect of the present disclosure, there is also provided apouch-type secondary battery in which a single unit of a sheet-typepouch exterior including two corresponding accommodating partsconfigured to mount an electrode assembly therebetween and symmetricallyformed at both sides by disposing a protruding part therebetween isfolded along two folding lines outside a center part of the protrudingpart by vertically mounting a side surface of the electrode assembly onthe protruding part, such that folded parts surround side edges of theelectrode assembly, and the accommodating parts are overlapped andthermally fused together.

A length of the pouch exterior between the two folding lines maycorrespond to a thickness of the electrode assembly such that an excessportion may not be generated between the folded parts.

A depth of a bottom edge of each accommodating part away from theprotruding part may be equal to or greater than ½ of the thickness ofthe electrode assembly, a depth of a bottom edge of the accommodatingpart close to the protruding part may be equal to or greater than ½ of avalue obtained by subtracting a width of a top surface of the protrudingpart from the thickness of the electrode assembly, and the bottom edgesof the two accommodating parts close to the protruding part may serve asthe two folding lines.

In another aspect of the present disclosure, there is also provided amethod of manufacturing a pouch-type secondary battery, the methodincluding preparing a pouch exterior according to the presentdisclosure, overlapping accommodating parts by vertically mounting aside surface of an electrode assembly on a protruding part and foldingthe pouch exterior along two folding lines in such a manner that foldedparts surround side edges of an electrode assembly, and thermally fusingsurrounding sides of the overlapped accommodating parts.

Herein, outer sides of the accommodating parts opposite the protrudingpart may be extended relatively long, and the accommodating parts may beoverlapped, sides of the accommodating parts other than the outer sidesmay be thermally fused, the outer sides of the accommodating parts maybe thermally fused after injecting an electrolyte therethrough, and thenthe outer sides of the accommodating parts may be partially cut.

The present disclosure provides a pouch exterior formed to prevent anunnecessary space of a folded part in a three-side sealed pouch-typesecondary battery.

The pouch exterior according to the present disclosure is not folded ata center part but is folded near bottom edges of accommodating parts,and thus does not need to give a margin of about 1.5 mm to 3 mm near thecenter part in consideration of folding like a conventional pouchexterior. Compared to the conventional case in which the pouch exteriorshould be folded near a center part of a side surface of an electrodeassembly and thus an unnecessary space is generated due to a bent shapeof the folded part, in the present disclosure, bent shapes of the foldedparts are moved aside to side edges of an electrode assembly. Therefore,an area for the electrode assembly in the pouch exterior may bemaximized without generating an unnecessary space in a cell and thus anenergy density of the cell may be increased. By preventing theunnecessary space of the folded parts, a cell capacity may be increasedand an energy density of a module/pack including the pouch-typesecondary battery may also be increased. In addition, since theunnecessary space of the folded parts is prevented, a module/packcooling structure and an assembly process may be simplified.

The pouch exterior according to the present disclosure may reduce adefect rate by preventing a rupture of the pouch exterior in amanufacturing process, may mount the electrode assembly at an accurateposition without an additional device, and may increase a lifetime ofthe battery by minimizing sealing parts contacting the air and reducingpossibilities of permeation of air, moisture, etc. and leakage of anelectrolyte.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate a preferred embodiment of thepresent disclosure and together with the foregoing disclosure, serve toprovide further understanding of the technical features of the presentdisclosure, and thus, the present disclosure is not construed as beinglimited to the drawing.

FIG. 1 is a top view of a pouch exterior of a conventional three-sidesealed pouch-type secondary battery.

FIG. 2 illustrates sequential cross-sectional views for describing amethod of manufacturing a pouch-type secondary battery using the pouchexterior of FIG. 1, taken along a line II-II′ of FIG. 1.

FIG. 3 is a top view of the pouch-type secondary battery manufacturedusing the method of FIG. 2.

FIG. 4 is an exploded perspective view of a pouch-type secondary batteryaccording to an embodiment of the present disclosure.

FIG. 5 is a top view of a pouch exterior included in FIG. 4.

FIG. 6 is a part of a cross-sectional view taken along a line VI-VI′ ofFIG. 5.

FIG. 7 is a cross-sectional view taken along a line VII-VII′ of FIG. 5.

FIG. 8 illustrates sequential cross-sectional views for describing amethod of manufacturing the pouch-type secondary battery using the pouchexterior of FIG. 5, taken along the line VI-VI′ of FIG. 5.

FIG. 9 is a top view of the pouch-type secondary battery manufacturedusing the method of FIG. 8.

FIG. 10 is a front view of a pouch exterior including accommodatingparts connected to each other, according to a comparative example.

FIG. 11 is a cross-sectional view of a battery module including thepouch-type secondary batteries according to the present disclosure.

FIG. 12 is a cross-sectional view of a battery module including theconventional pouch-type secondary batteries each having, for example, afolded part of FIG. 3, according to a comparative example of FIG. 11.

FIG. 13 is a photographic image of the conventional three-side sealedpouch-type secondary battery.

FIGS. 14 and 15 are photographic images of the pouch exterior accordingto the present disclosure.

FIG. 16 is a photographic image of the pouch-type secondary batteryaccording to the present disclosure.

DETAILED DESCRIPTION

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings. Priorto the description, it should be understood that the terms used in thespecification and the appended claims should not be construed as limitedto general and dictionary meanings, but interpreted based on themeanings and concepts corresponding to technical aspects of the presentdisclosure on the basis of the principle that the inventor is allowed todefine terms appropriately for the best explanation. Therefore, thedescription proposed herein is just a preferable example for the purposeof illustrations only, not intended to limit the scope of thedisclosure, so it should be understood that other equivalents andmodifications could be made thereto without departing from the scope ofthe disclosure.

FIG. 4 is an exploded perspective view of a pouch-type secondary battery100 according to an embodiment of the present disclosure. FIG. 5 is atop view of a pouch exterior 300 included in FIG. 4. FIG. 6 is a part ofa cross-sectional view taken along a line VI-VI′ of FIG. 5. FIG. 7 is across-sectional view taken along a line VII-VII′ of FIG. 5.

Initially, referring to FIG. 4, the pouch-type secondary battery 100includes an electrode assembly 200 and the pouch exterior 300.

The electrode assembly 200 may be a stacked electrode assembly in whicha plurality of positive and negative plates cut to a predetermined sizeare stacked on one another by disposing a separator therebetween. Apositive electrode 210 and a negative electrode 220 of the electrodeassembly 200 protrude in opposite directions from both sides of thepouch exterior 300.

Two corresponding accommodating parts 310 a and 310 b are formed in thepouch exterior 300 according to the present disclosure. A protrudingpart 315 is generated between the accommodating parts 310 a and 310 bsuch that the accommodating parts 310 a and 310 b are not connected toeach other. The accommodating part 310 a at a side may have a widthcorresponding to a bottom surface (not shown) of the electrode assembly200, and the accommodating part 310 b at the other side may have a widthcorresponding to a top surface 240 of the electrode assembly 200.

A width P of a top surface of the protruding part 315 is greater thanzero and less than a thickness t of the electrode assembly 200. Comparedto a conventional case in which accommodating parts are spaced apartfrom each other by a distance greater than the thickness of an electrodeassembly and are further spaced apart from each other in considerationof a margin of about 1.5 mm to 3 mm, the width P of the top surface ofthe protruding part 315 less than the thickness t of the electrodeassembly 200 is smaller than that of the conventional case.

Since the width P of the top surface of the protruding part 315 shouldbe less than the thickness t of the electrode assembly 200, when thepouch exterior 300 is compressed to generate the two adjacentaccommodating parts 310 a and 310 b, a material, method, or mold designfor forming the pouch exterior 300 may be changed to prevent a reductionin mechanical strength or a rupture of the protruding part 315 betweenthe two accommodating parts 310 a and 310 b closer than the conventionalcase. However, since a forming depth is not increased compared to theconventional case, as to be shown in a test example described below, thepouch exterior 300 may be produced without being ruptured.

Herein, reference numerals 320, 330, and 350 denote upper sealing parts,lower sealing parts, and side sealing parts, respectively.

In a preferable example, the pouch exterior 300 may have a structure inwhich outer sides of the accommodating parts 310 a and 310 b oppositethe protruding part 315, i.e., the side sealing parts 350, are extendedrelatively long. In this case, the pouch-type secondary battery 100 maybe manufactured by overlapping the accommodating parts 310 a and 310 bto accommodate the electrode assembly 200 therebetween, sealing allsealing parts (contact parts) other than the extended side sealing parts350, i.e., the upper sealing parts 320 and the lower sealing parts 330,sealing the side sealing parts 350 after injecting an electrolytetherethrough, and cutting the side sealing parts 350 to a predeterminedsize. Based on the above-described structure of the pouch exterior 300,the electrolyte may be easily injected and may be prevented fromoverflowing due to a user mistake.

The pouch exterior 300 may be configured as a laminate sheet including ametal layer and a resin layer. Particularly, the laminate sheet may bean aluminum laminate sheet. The pouch exterior 300 includes a core layerconfigured as a metal layer, a thermosetting layer generated on a topsurface of the core layer, and an insulating layer generated on a bottomsurface of the core layer. The thermosetting layer may be made ofpolymer resin, e.g., modified polypropylene such as casted polypropylene(CPP), to serve as an adhesive layer, and the insulating layer may bemade of nylon or resin such as polyethylene terephthalate (PET).However, the structure and material of the pouch exterior 300 are notlimited thereto.

The accommodating parts 310 a and 310 b of the pouch exterior 300 may besimultaneously formed in a single process by compressing the aluminumlaminate sheet using a die and a punch based on a deep drawing method.

Further referring to FIGS. 5 to 7, a depth t1 of a bottom edge a1 of theaccommodating part 310 a away from the protruding part 315 is equal toor greater than ½ of the thickness t of the electrode assembly 200 and,likewise, a depth t1 of a bottom edge b1 of the accommodating part 310 baway from the protruding part 315 is equal to or greater than ½ of thethickness t of the electrode assembly 200. The depth t1 of the bottomedge a1 and the depth t1 of the bottom edge b1, which are equal to ½ ofthe thickness t of the electrode assembly 200, may not waste a space andthus may be ideal. However, some products may require slightly largerdepths for an extra space to achieve convenience in processing.Therefore, the depth t1 of the bottom edge a1 and the depth t1 of thebottom edge b1 may be equal to or greater than ½ of the thickness t ofthe electrode assembly 200.

A depth t2 of a bottom edge a2 of the accommodating part 310 a close tothe protruding part 315 and a depth t2 of a bottom edge b2 of theaccommodating part 310 b close to the protruding part 315, whichcorrespond to a height of the protruding part 315, is ½ of a valueobtained by subtracting the width P of the top surface of the protrudingpart 315 from the thickness t of the electrode assembly 200.

The bottom edge a2 of the accommodating part 310 a close to theprotruding part 315 and the bottom edge b2 of the accommodating part 310b close to the protruding part 315 serve as folding lines F1 and F2later. The accommodating part 310 a at a side and the accommodating part310 b at the other side are mirror-symmetric with respect to a centerpart F.

As particularly shown in FIG. 6, each of the accommodating parts 310 aand 310 b has an inclined bottom surface. The depth t1 of the bottomedge a1 of the accommodating part 310 a away from the protruding part315 is greater than the depth t2 of the bottom edge a2 of theaccommodating part 310 a close to the protruding part 315. Likewise, thedepth t1 of the bottom edge b1 of the accommodating part 310 b away fromthe protruding part 315 is greater than the depth t2 of the bottom edgeb2 of the accommodating part 310 b close to the protruding part 315. Ifthe width P of the top surface of the protruding part 315 is increased,a difference between the depth t1 and the depth t2 is also increased.Otherwise, if the width P of the top surface of the protruding part 315is reduced, the difference between the depth t1 and the depth t2 is alsoreduced. The width P of the top surface of the protruding part 315 maybe determined in consideration of a material, an elongation rate, etc.of the pouch exterior 300.

In the conventional case, the accommodating parts have a constant depthcorresponding to about a half of the thickness of the electrode assemblyand bottom surfaces of the accommodating parts are not inclined. On thecontrary, the accommodating parts 310 a and 310 b of the presentdisclosure have a maximum depth of the depth t1 equal to or greater than½ of the thickness t of the electrode assembly 200 and have a minimumdepth of the depth t2 corresponding to ½ of the value obtained bysubtracting the width P of the top surface of the protruding part 315from the thickness t of the electrode assembly 200. In addition, thebottom surfaces thereof are gradually inclined from an edge having themaximum depth to another edge having the minimum depth.

As described above, the pouch exterior 300 of the present disclosurediffers from the conventional pouch exterior in the depth, the shape ofbottom surfaces of two accommodating parts, and the width of aprotruding part between the accommodating parts. The depth of the pouchexterior 300 of the present disclosure is smaller. The bottom surfacesof the accommodating parts 310 a and 310 b of the pouch exterior 300 ofthe present disclosure are inclined. The width of the protruding part315 of the pouch exterior 300 of the present disclosure is smaller.

FIG. 8 illustrates sequential cross-sectional views for describing amethod of manufacturing the pouch-type secondary battery 100 using thepouch exterior 300 of FIG. 5, taken along the line VI-VI′ of FIG. 5.FIG. 9 is a top view of the pouch-type secondary battery 100manufactured using the method of FIG. 8.

FIG. 8(a) is a cross-sectional view showing that the pouch exterior 300is formed in a spread state. Then, a side surface 230 of the electrodeassembly 200 having the thickness t is vertically mounted on theprotruding part 315 at the center of the pouch exterior 300 as shown inFIG. 8(b), and the pouch exterior 300 is folded and the twoaccommodating parts 310 a and 310 b are overlapped to cover both sidesof the electrode assembly 200 in the order of FIG. 8(c) and FIG. 8(d).

Referring to FIG. 4 together, the side surface 230 of the electrodeassembly 200 is mounted on the protruding part 315 in such a manner thatthe positive electrode 210 and the negative electrode 220 are located tocorrespond to the upper sealing parts 320 and the lower sealing parts330, and the pouch exterior 300 is folded in such a manner that theupper sealing parts 320, the lower sealing parts 330, and the sidesealing parts 350 individually contact each other.

In this case, instead of folding the center part F between theaccommodating parts 310 a and 310 b as in the conventional case, thepouch exterior 300 is folded along the two folding lines F1 and F2outside the center part F of the protruding part 315, i.e., the foldingline F1 based on the bottom edge a2 of the accommodating part 310 aclose to the protruding part 315 and the folding line F2 based on thebottom edge b2 of the accommodating part 310 b close to the protrudingpart 315. A length of the pouch exterior 300 between the two foldinglines F1 and F2 nearly corresponds to the thickness t of the electrodeassembly 200, and thus the side surface 230 of the electrode assembly200 may be covered without unnecessarily wasting a space. The pouchexterior 300 may be easily folded along the pre-formed bottom edges a2and b2, may not be wrinkled, and may be firmly sealed in a subsequentprocess. As described above, differently from the conventional case inwhich a pouch exterior is folded along a single folding linecorresponding to a center part between the two accommodating parts andthus the folded part serves as an excess portion along a center part ofa side surface of the electrode assembly, in the present disclosure,since the pouch exterior 300 is folded along the two folding linesoutside the center part and the folded parts are moved aside to surroundside edges of the electrode assembly 200, no excess portion is generatedat the side surface of the electrode assembly 200.

Referring to FIG. 9, it is shown that no excess portion is generated ata non-sealed right side surface of the pouch-type secondary battery 100unlike the conventional case. As described above, if the length of thepouch exterior 300 between the two folding lines F1 and F2 correspondsto the thickness t of the electrode assembly 200, no excess portion isgenerated between the folded parts.

If the protruding part 315 is not generated and the accommodating parts310 a and 310 b are fully connected to each other, since a part of anouter circumferential surface of the pouch exterior 300 is deformed whenthe pouch exterior 300 is folded, a structurally stable battery may notbe manufactured as shown in FIG. 10 illustrating a pouch exterior havingno protruding part according to a comparative example.

FIG. 10 is a front view of a pouch exterior 400 including accommodatingparts connected to each other, according to a comparative example.

Referring to FIG. 10, when the pouch exterior 400 is folded with respectto a point A, a lower part 302 of the pouch exterior 400 receives alarge tensile force in arrow directions. Since the pouch exterior 400 isconfigured as a very thin laminate sheet as described above, suchtensile force may break the lower part 302 of the pouch exterior 400.

Accordingly, in the pouch exterior 400 illustrated in FIG. 10, the pouchexterior 400 should be folded with respect to a point B located on abottom surface thereof. However, if the pouch exterior 400 is folded asdescribed above, deformation occurs near the point B and thus an upperpart 301 of the pouch exterior 400 is bent toward the point B and isdeformed. Therefore, a normal battery capable of maintaining sealabilitymay not be manufactured.

However, in the present disclosure, since the bottom edges a2 and b2having a predetermined depth should be generated to provide theprotruding part 315 and the pouch exterior 300 is folded along thefolding lines F1 and F2 based on the bottom edges a2 and b2, excessivedeformation does not occur near the folded parts.

As described above, the present disclosure may provide a pouch-typesecondary battery for folding a pouch exterior along two folding linesby changing a formed shape of the pouch exterior in such a manner thatthe folded parts surround side edges of an electrode assembly, thebattery being capable of stably sealing the electrode assembly withoutunnecessarily wasting a space near the folded parts, and of maximizingan area for the electrode assembly in the pouch exterior, and beingusable as a high-capacity and high-density electric vehicle battery anda high-capacity secondary battery, and a method of manufacturing thesame.

After the process of FIG. 8(d) in which the pouch exterior 300 is foldedand overlapped in such a manner that the upper sealing parts 320, thelower sealing parts 330, and the side sealing parts 350 of FIG. 4individually contact each other, the upper sealing parts 320 and thelower sealing parts 330 may be thermally fused, the side sealing parts350 may be thermally fused after injecting an electrolyte through a gaptherebetween, and then the side sealing parts 350 may be cut to apredetermined length.

Although the positive electrode 210 and the negative electrode 220 ofthe electrode assembly 200 protrude in opposite directions in theabove-described pouch-type secondary battery 100, an electrode assemblyincluding a positive electrode and a negative electrode protruding inthe same direction may also be manufactured to a pouch-type secondarybattery using the pouch exterior 300 according to the presentdisclosure.

A plurality of the pouch-type secondary batteries 100 of FIG. 9according to the present disclosure may be stacked on one another tomanufacture a battery module/pack. FIG. 11 is a cross-sectional view ofa battery module 500 including the pouch-type secondary batteries 100according to the present disclosure.

Referring to FIG. 11, in the battery module 500, a plurality of thepouch-type secondary batteries 100 may be stacked on one another andnon-sealed surfaces thereof may be located at a lower side and attachedto a top surface of a cooling plate 600. For example, surfaces of thepouch-type secondary batteries 100 corresponding to the right sidesurface in the configuration of FIG. 9 may be located at the lower sideand may be attached to the top surface of the cooling plate 600.Compared to sealed surfaces, since the non-sealed surfaces do not haveunnecessarily protruding parts, the pouch-type secondary batteries 100may fully and closely contact the cooling plate 600 and the structure ofthe top surface of the cooling plate 600 may be simplified.

FIG. 12 is a cross-sectional view of a battery module including theconventional pouch-type secondary batteries 40 each having, for example,the folded part w of FIG. 3, according to a comparative example of FIG.11.

Since the pouch-type secondary batteries 40 have the folded parts w, acooling plate 600′ should be generated in a complicated shape having atleast slits H into which the folded parts w are inserted. If a coolingplate having wider grooves is generated to accommodate the folded partsw therein, a contact area between the pouch-type secondary batteries 40and the cooling plate may be reduced and sufficient cooling performancemay not be easily expected.

As comparatively shown in FIGS. 11 and 12, according to theconfiguration of the present disclosure, the pouch-type secondarybatteries 100 and the cooling plate 600 may be located closer to eachother compared to the conventional case. That is, since the non-sealedsurfaces do not have unnecessarily protruding parts, the cooling plate600 and the pouch-type secondary batteries 100 may fully and closelycontact each other. Therefore, a total volume of the battery module 500may be reduced and thus an energy density may be increased. Furthermore,according to the above-described configuration of the presentdisclosure, the maximum contact area between the pouch-type secondarybatteries 100 and the cooling plate 600 may be ensured and thus heattransfer efficiency may be increased. Accordingly, heat generated fromthe electrode assemblies in the pouch-type secondary batteries 100 maybe rapidly and appropriately transferred to the cooling plate 600 andthus cooling efficiency may be increased. In addition, although thefolded parts w should be individually inserted into the slits H toassemble the battery module of FIG. 12, in the present disclosure, suchprocess may not be necessary and thus the assembly process may besimplified.

FIG. 13 is a photographic image of the conventional three-side sealedpouch-type secondary battery 40.

Referring to FIG. 13, the conventional three-side sealed pouch-typesecondary battery 40 obtains the folded part w when the three sides aresealed. The folded part w has a length of about 2.5 mm and protrudesfrom a side surface of the electrode assembly 30.

FIGS. 14 and 15 are photographic images of the pouch exterior 300according to the present disclosure. FIG. 14 is a top view showing aninner surface of the pouch exterior 300, and FIG. 15 is a bottom viewshowing an outer surface of the pouch exterior 300.

As shown in FIGS. 14 and 15, the pouch exterior 300 according to thepresent disclosure may be formed without being ruptured or torn. It isalso shown that the accommodating parts 310 a and 310 b and theprotruding part 315 may be formed as desired without any distortion orconcentration of stress.

FIG. 16 is a photographic image of the pouch-type secondary battery 100manufactured using the pouch exterior 300, according to the presentdisclosure.

As comparatively shown in FIGS. 16 and 13, the pouch-type secondarybattery 100 according to the present disclosure does not have anunnecessarily protruding part on a non-sealed surface. A flat shape of aside surface of an electrode assembly is maintained on a side surface ofthe pouch-type secondary battery 100. As described above, compared tothe conventional case in which the pouch exterior 10 should be foldednear a center part of the side surface of the electrode assembly 30 andthus an unnecessary space such as the folded part w of FIG. 13 isgenerated due to a bent shape of the folded part, in the presentdisclosure, since bent shapes of the folded parts of the pouch exterior300 may be moved aside to side edges of the electrode assembly 200, theunnecessary space may be prevented from the non-sealed surface and thusa cell capacity may be increased. Furthermore, an energy density of amodule/pack including the pouch-type secondary battery 100 may beincreased. In addition, since the unnecessary space is prevented, amodule/pack cooling structure and an assembly process may be simplified.

The present disclosure has been described in detail. However, it shouldbe understood that the detailed description and specific examples, whileindicating preferred embodiments of the disclosure, are given by way ofillustration only, since various changes and modifications within thescope of the disclosure will become apparent to those skilled in the artfrom this detailed description.

What is claimed is:
 1. A pouch exterior, comprising: two correspondingaccommodating parts configured to mount an electrode assemblytherebetween and symmetrically formed at both sides of a protrudingpart, and configured to be folded along two folding lines outside acenter of the protruding part by mounting a side surface of theelectrode assembly on the protruding part, such that folded parts of thepouch exterior surround side edges of the electrode assembly.
 2. Thepouch exterior of claim 1, wherein a length of the pouch exteriorbetween the two folding lines corresponds to a thickness of theelectrode assembly.
 3. The pouch exterior of claim 1, wherein a depth ofa bottom edge of each accommodating part away from the protruding partis greater than a depth of a bottom edge of the accommodating part closeto the protruding part such that a bottom surface of the accommodatingpart is inclined.
 4. The pouch exterior of claim 1, wherein a width of atop surface of the protruding part is greater than zero and less than athickness of the electrode assembly.
 5. The pouch exterior of claim 1,wherein a depth of a bottom edge of each accommodating part away fromthe protruding part is equal to or greater than ½ of a thickness of theelectrode assembly.
 6. The pouch exterior of claim 5, wherein a depth ofa bottom edge of the accommodating part close to the protruding part isequal to or greater than ½ of a value obtained by subtracting a width ofa top surface of the protruding part from the thickness of the electrodeassembly.
 7. The pouch exterior of claim 5, wherein bottom edges of thetwo accommodating parts close to the protruding part serve as the twofolding lines.
 8. The pouch exterior of claim 1, wherein a length of thepouch exterior between the two folding lines corresponds to a thicknessof the electrode assembly such that an excess portion is not generatedbetween the folded parts.
 9. A pouch-type battery, comprising: asheet-type pouch exterior including two corresponding accommodatingparts configured to mount an electrode assembly therebetween andsymmetrically formed at both sides of a protruding part, wherein thesheet-type pouch exterior is configured to be folded along two foldinglines outside a center of the protruding part by mounting a side surfaceof the electrode assembly on the protruding part, such that folded partsof the pouch exterior surround side edges of the electrode assembly, andthe accommodating parts overlap.
 10. The pouch-type battery of claim 9,wherein the accommodating parts are thermally fused together.
 11. Thepouch-type secondary battery of claim 9, wherein a length of the pouchexterior between the two folding lines corresponds to a thickness of theelectrode assembly such that an excess portion is not generated betweenthe folded parts.
 12. The pouch-type secondary battery of claim 9,wherein a depth of a bottom edge of each accommodating part away fromthe protruding part is equal to or greater than ½ of the thickness ofthe electrode assembly, wherein a depth of a bottom edge of theaccommodating part close to the protruding part is equal to or greaterthan ½ of a value obtained by subtracting a width of a top surface ofthe protruding part from the thickness of the electrode assembly, andwherein the bottom edges of the two accommodating parts close to theprotruding part serve as the two folding lines.
 13. A method ofmanufacturing a pouch-type battery, the method comprising: preparing apouch exterior including two accommodating parts configured to mount anelectrode assembly therebetween and symmetrically formed at both sidesby disposing a protruding part therebetween, and folded along twofolding lines outside a center of the protruding part by mounting a sidesurface of the electrode assembly on the protruding part, such thatfolded parts of the pouch exterior surround side edges of the electrodeassembly; overlapping the accommodating parts by mounting the sidesurface of the electrode assembly on the protruding part and folding thepouch exterior along the two folding lines in such a manner that thefolded parts surround the side edges of the electrode assembly; andthermally fusing surrounding sides of the overlapped accommodatingparts.
 14. The method of claim 13, wherein the accommodating parts areoverlapped, sides of the accommodating parts other than outer sides arethermally fused, the outer sides of the accommodating parts arethermally fused after injecting an electrolyte therethrough, and thenthe outer sides of the accommodating parts are partially cut.
 15. Themethod of claim 13, wherein a length of the pouch exterior between thetwo folding lines corresponds to a thickness of the electrode assemblysuch that an excess portion is not generated between the folded parts.16. The method of claim 13, wherein a depth of a bottom edge of eachaccommodating part away from the protruding part is equal to or greaterthan ½ of a thickness of the electrode assembly, wherein a depth of abottom edge of the accommodating part close to the protruding part is ½of a value obtained by subtracting a width of a top surface of theprotruding part from the thickness of the electrode assembly, andwherein the bottom edges of the two accommodating parts close to theprotruding part serve as the two folding lines.